This invention relates to a C-shaped compliant contact composed of a connection portion adapted to be connected to an electric cable or the like, a press-fitting portion adapted to be press-fitted in a through-hole of a printed circuit board, and a contact portion adapted to be in contact with a contact of a mating connector, and more particularly to a C-shaped compliant contact capable of preventing from bending when it is being inserted into a through-hole of a printed circuit board.
A hitherto used C-shaped compliant contact will be explained by referring to FIGS. 5 to 6. FIG. 5 illustrates the press-fitting portion 16 and the connection portion 18 of the C-shaped compliant contact 40 of the prior art in a partly perspective view. FIGS. 6A, 6B and 6C illustrate the C-shaped compliant contact of the prior art in a plan view, a longitudinal sectional view taken along the line A--A in FIG. 5 and a cross-sectional view taken along the line B--B in FIG. 5, respectively. FIG. 7 illustrates the C-shaped compliant contact of the prior art in various states in one drawing from the first step to the last step for press-fitting the contact into a printed circuit board.
In general, the C-shaped compliant contact is made of a springy copper alloy such as phosphor bronze, beryllium copper or the like. It is best to manufacture the C-shaped compliant contact so as to apply uniform stresses onto the inner surface of the through-hole of a printed circuit board in which the press-fitting portion of the contact has been press-fitted.
In order to fulfil such a requirement, the applicant has proposed in Japanese Patent Application Opened No. H8-31,476 a C-shaped compliant contact 40 including a press-fitting portion 16 having an inner periphery forming a U-shaped groove having two arc portions 28 and a straight portion 30 therebetween so that the circle inscribing the U-shaped inner periphery is in an eccentric relation to the two arc portions 28. The thickness of the arc portions 28 become progressively thinner on proceeding toward the open end of the U-shaped groove so as to make longer the length of the arc portions 28 contacting the through-hole 26 of a printed circuit board as much as possible.
With such a proposed C-shaped compliant contact 40, because of the spring-like property of the walls of the U-shaped groove of the press-fitting portion 16 and because of the arc-shaped outer periphery to be press-fitted in the through-hole 26, the press-fitting portion 16 elastically deforms and contacts the through-hole 26 with wide contacting surfaces, thereby achieving a uniform deformation of the printed circuit board 24.
The C-shaped compliant contact 40 of the prior art has the press-fitting portion 16 constructed as described above and the thickness of the arc portions 28 becoming thinner on proceeding toward the ends of the walls of the U-shaped groove. When the contact 40 is being inserted into the through-hole 26 of a printed circuit board 24, the walls of the U-shaped groove are forced toward each other as shown by arrows P and Q in FIG. 5 so as to reduce the size of that portion to facilitate the insertion into the through-hole 26. As a result, a force will act on the inner surface 19 in the groove 22 of the contact 40 in a direction (toward the connection portion 18) as shown by an arrow R in FIG. 6B so that the connection portion 18 will be bent in the direction opposite to the outer surface 17 of the connection portion 18, which is a problem to be solved.
As shown at the lowermost position in FIG. 7, the distal end of the connection portion 18 of the contact 40 is shifted by a distance of the order of 0.8 to 0.85 mm away from the extension D of the outer line of the contact 40 which has press-fitted in the through-hole 26 of the printed circuit board 24.